1. Field of the Invention
The present invention relates to an improvement of sheet loading performance in a sheet loading device on which a sheet subjected to a specified processing is loaded.
2. Description of the Related Art
Hitherto, there is known a post-processing apparatus which can perform post-processing, such as staple processing or simple bookbinding processing, on a sheet subjected to print processing in an image forming apparatus. The post-processing apparatus includes a sheet loading device which discharges the sheet subjected to the foregoing specified post-processing to the outside of the apparatus and is for loading the discharged processed sheet.
In the related art sheet loading device, in order to enable more processed sheets to be loaded on a loading tray, following contrivances are made.
(1) A structure is made such that an inclined surface with a fixed inclined angle is provided on the loading surface of the loading tray, and the processed sheet discharged from the post-processing apparatus slides down along the inclined surface to the front end of the inclined tray.
(2) In order to downward press the center portion of the processed sheet loaded on the loading tray and to lower the loading height of the sheet loaded on the loading tray (to ensure an interval between a sheet discharge port in the post-processing apparatus and the sheet upper surface on the loading tray), a pressing member is provided above the loading tray.
In the related art loading device, the loadable number of sheets is set according to the size of a processed sheet, the number of bound sheets and the like, and when the number of sheets loaded on the loading tray exceeds the loadable number of sheets, a full-loading state signal is sent to the image forming apparatus.
In the related art sheet loading device, there is a fear that disadvantages as described below occur.
In general, the center portion of a booklet to which a simple bookbinding processing has been performed by the post-processing apparatus often expands. Thus, when many booklets are loaded on the loading tray, the expansions of the center portions of the booklets overlap with each other, press force at a contact position between the pressing member and the upper surface of the loaded booklet is increased, and the transport load of a next discharged booklet at the time of discharging onto the loading tray is remarkably increased. FIG. 9 is a view showing an example of poor sheet discharging caused by the increase of the transport load due to the overlap of the expansions of the booklet center portions in the related art post-processing apparatus.
In the case where a sheet (A3/LD, etc.) having a large size in the sheet transport direction is discharged from the post-processing apparatus, when the discharged sheet passes through the contact position between the pressing member and the upper surface of the loaded booklet, since it is sent in a state where the rear edge of the booklet is nipped by discharge rollers, stable sheet discharge (transport onto the loading tray) is performed. On the other hand, with respect to a sheet (LG, etc.) in which the size in the sheet transport direction is small, there is a case where after the sheet is discharged by the discharge rollers, the leading edge of the sheet is stopped by the load at the contact position between the pressing member and the upper surface of the loaded booklet, and can not be transported to a desired position on the loading tray. When the poor transport is repeated, the rear edge of the sheet discharged from the post-processing apparatus eventually blocks a sheet discharge port of the post-processing apparatus, and the poor sheet discharging is caused.
In the related art sheet loading device, in the case where the poor sheet discharging occurs, parameters, such as the size, the number of bound sheets and the number of loaded sheets, in which the poor sheet discharging occurs are confirmed, and the specifications are reviewed so that the full-loading state signal is transmitted to the image forming apparatus before reaching the initially set number of loaded sheets.